'use strict';

const NOTES_MAX_LENGTH = 5000;

const toNonNegativeNumber = (value) => {
  const n = Number(value);
  if (!Number.isFinite(n) || n < 0) return 0;
  return n;
};

const normalizeDiscount = (discount, amount) => {
  return Math.min(toNonNegativeNumber(discount), toNonNegativeNumber(amount));
};

const getPayableAmount = (payment = {}) => {
  const amount = toNonNegativeNumber(payment.amount);
  return amount - normalizeDiscount(payment.discount, amount);
};

const sanitizeNotes = (notes) => {
  if (notes == null) return '';
  return String(notes).trim().slice(0, NOTES_MAX_LENGTH);
};

module.exports = {
  NOTES_MAX_LENGTH,
  getPayableAmount,
  normalizeDiscount,
  sanitizeNotes
};